CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Liaoning Province Key Laboratory of Metabolomics, Dalian 116023, China.
Anal Chem. 2024 Sep 17;96(37):14935-14943. doi: 10.1021/acs.analchem.4c02989. Epub 2024 Sep 2.
Macrophages consist of a heterogeneous population of functionally distinct cells that participate in many physiological and pathological processes. They exhibit prominent plasticity by changing their different functional phenotypes represented by proinflammatory (M1) and anti-inflammatory (M2) in response to different environmental stimuli. Emerging evidence illustrates the importance of intracellular metabolic pathways in macrophage polarizations and functions. In the tumor microenvironment (TME), macrophages tend to M2 polarization, which promotes tumor growth and leads to adverse physiological effects. Due to the lack of highly specific antigens in M1 and M2 macrophages, significant challenges present in isolating these subtypes from clinical samples or in vitro coculture models of tumor-immune cells. In reverse, the single-cell technique provides the possibility to investigate the factors influencing macrophage polarization in the TME. In this research, we employed inertial microfluidic chip-mass spectrometry (IMC-MS) to conduct single-cell metabolomics analysis of macrophages polarized into the two major phenotypes, respectively, and 213 metabolites were identified in total. Subsequently, differential metabolites between macrophage phenotypes were analyzed using volcano plots and binary logistic regression models. Glutamine was pinpointed as a key metabolite for the M1 and M2 phenotypes. Experimental results from both monoculture and coculture cell models demonstrated that M1 polarization is more reliant on the presence of glutamine in the culture environment than M2 polarization. Glutamine deficiency resulted in failed M1 polarization, while its absence had a less pronounced effect on M2 polarization. Replenishing an appropriate amount of glutamine during the intermediate stages of coculture models significantly enhanced the proportion of M1 polarization and suppressed the growth of tumor cells. This research elucidated glutamine as a key factor influencing macrophage polarization in the TME via single-cell metabolomics based on IMC-MS, offering promising insights and targets for tumor therapies.
巨噬细胞是由功能不同的细胞组成的异质性群体，参与许多生理和病理过程。它们通过改变其不同的功能表型（促炎型（M1）和抗炎型（M2））来响应不同的环境刺激，表现出明显的可塑性。新出现的证据表明，细胞内代谢途径在巨噬细胞极化和功能中起着重要作用。在肿瘤微环境（TME）中，巨噬细胞倾向于 M2 极化，这促进了肿瘤的生长，并导致了不利的生理效应。由于 M1 和 M2 巨噬细胞缺乏高度特异性的抗原，因此从临床样本或肿瘤免疫细胞的体外共培养模型中分离这些亚型存在很大的挑战。相反，单细胞技术为研究 TME 中影响巨噬细胞极化的因素提供了可能性。在这项研究中，我们采用惯性微流控芯片-质谱（IMC-MS）对分别极化的两种主要表型的巨噬细胞进行单细胞代谢组学分析，总共鉴定出 213 种代谢物。随后，使用火山图和二元逻辑回归模型分析巨噬细胞表型之间的差异代谢物。谷氨酰胺被确定为 M1 和 M2 表型的关键代谢物。单核和共培养细胞模型的实验结果表明，M1 极化比 M2 极化更依赖于培养环境中谷氨酰胺的存在。谷氨酰胺缺乏导致 M1 极化失败，而对 M2 极化的影响则不明显。在共培养模型的中间阶段补充适量的谷氨酰胺可显著提高 M1 极化的比例，并抑制肿瘤细胞的生长。这项研究通过基于 IMC-MS 的单细胞代谢组学阐明了谷氨酰胺作为影响 TME 中巨噬细胞极化的关键因素，为肿瘤治疗提供了有前景的见解和靶点。
